Lithographic apparatus and device manufacturing method

Abstract

A difficulty of contamination interfering with a grid plate positional measurement system is addressed. In one embodiment contamination is prevented from coming into contact with the grating or the sensor. In an embodiment, surface acoustic waves are used to detach contamination from a surface of the grating or sensor.

The invention claimed is: 
     
       1. A substrate table for a lithographic apparatus, the table comprising:
 a support body configured to hold a substrate, the support body having a surface arranged to surround, and be essentially co-planar with, the substrate when supported on the support body; and 
 a grid structure outward of the surface, the grid structure having a grating arranged to redirect radiation toward a sensor configured to detect the redirected radiation to measure a position of the table, 
 wherein at least part of the grid structure is removable, relative to the surface, from the support body. 
 
     
     
       2. The table of  claim 1 , wherein a surface of the grid structure is liquidphobic or has a liquidphobic coating. 
     
     
       3. The table of  claim 1 , wherein an upper surface of the grid structure is horizontally spaced apart by an open gap from the surface of the support body. 
     
     
       4. A lithographic apparatus comprising:
 the table of  claim 3 ; 
 a projection system configured to project a radiation beam onto a substrate supported by the table; and 
 a liquid supply system configured to supply liquid to a space between the projection system and the substrate or table. 
 
     
     
       5. The table of  claim 1 , comprising a plurality of separate grid structures located around a central portion of the support body, each of the grid structures having at least a part thereof removable, relative to the surface, from the support body. 
     
     
       6. The table of  claim 1 , further comprising a temperature conditioning device configured to supply or removal thermal energy from the grid structure. 
     
     
       7. The table of  claim 1 , wherein the grid structure is in rectilinear arrangement around the surface. 
     
     
       8. A substrate table for a lithographic apparatus, the table comprising:
 a support body having a surface arranged to surround, and be essentially co-planar with, a substrate when supported on the support body; and 
 a measurement system component outward of the surface, the measurement system component either comprising a sensor configured to detect radiation redirected by a grating to measure a relative position between the table and the grating or comprising the grating, 
 wherein at least part of the measurement system component is removable, relative to the surface, from the support body. 
 
     
     
       9. The table of  claim 8 , wherein an upper surface of the measurement system component is horizontally spaced apart by an open gap from the surface of the support body. 
     
     
       10. The table of  claim 8 , wherein a surface of the measurement system component is liquidphobic or has a liquidphobic coating. 
     
     
       11. The table of  claim 8 , comprising a plurality of separate measurement system components located around a central portion of the support body, each of the measurement system component having at least a part thereof removable, relative to the surface, from the support body. 
     
     
       12. The table of  claim 8 , further comprising a temperature conditioning device configured to supply or removal thermal energy from the grid structure. 
     
     
       13. The table of  claim 8 , wherein the grid structure is in rectilinear arrangement around the surface. 
     
     
       14. A lithographic apparatus comprising:
 the table of  claim 8 ; 
 a projection system configured to project a radiation beam onto a substrate supported by the table; and 
 a liquid supply system configured to supply liquid to a space between the projection system and the substrate or table. 
 
     
     
       15. A substrate table for a lithographic apparatus, the table comprising:
 a support body having a surface arranged to surround, and be essentially co-planar with, a substrate when supported on the support body; and 
 a grid structure outward of the surface, the grid structure having at least 4 rectangular shaped gratings arranged along different sides of the substrate table and each of the gratings arranged to redirect radiation toward a sensor configured to detect the redirected radiation to measure a position of the table, 
 wherein at least part of the grid structure is removable, relative to the surface, from the support body. 
 
     
     
       16. The table of  claim 15 , wherein an upper surface of the grid structure is horizontally spaced apart by an open gap from the surface of the support body. 
     
     
       17. The table of  claim 15 , wherein a surface of the grid structure component is liquidphobic or has a liquidphobic coating. 
     
     
       18. The table of  claim 15 , each of the gratings having at least a part thereof removable, relative to the surface, from the support body. 
     
     
       19. The table of  claim 15 , further comprising a temperature conditioning device configured to supply or removal thermal energy from the grid structure. 
     
     
       20. A lithographic apparatus comprising:
 the table of  claim 15 ; 
 a projection system configured to project a radiation beam onto a substrate supported by the table; and 
 a liquid supply system configured to supply liquid to a space between the projection system and the substrate or table.